This invention relates to a securing device for a housing cover element. The invention relates more particularly to a securing device for switch boxes having electrical switching devices, having at least one screwable element which can be threaded to the housing and which is secured undetachably to the cover element by a stop on its shaft penetrating the cover element, wherein each screwable element extends through an indentation in the surface of the cover element in which a pre-stressed compression spring is disposed between a shoulder of the screw element and the base of the indentation.
A securing device of the type described above is known from West-German published design application No. 78 24 594, in which a sheath provided with an indentation is secured on a cover element, namely the cap, of an electrical appliance. A securing bolt penetrates the indentation, a pre-stressed compression spring is disposed between the head of the bolt and the base of the indentation. The securing bolt penetrates a corresponding opening in the base of the sheath. On a free end, the securing bolt has a cylindrical cross-piece which, in order to fix the cover element on the electrical appliance, is disposed behind corresponding stop faces on the appliance by a partial circular rotation of the securing bolt. With this securing device, only the cover element can be secured releasably on the housing of the appliance.
From West-German published patent application No. 962,725, a snap closure for the housing of electrical appliances is known in which a securing bolt penetrates a bore in the housing cap. The securing bolt is provided on its outer end with an actuation grip. On its inner end, it is provided with a protrusion which can be guided into guide paths of a cover body attached to the housing by means of a partial circular rotation and fixed there. Between the interior of the cap and a disc resting loosely against the protrusion, there is a pre-stressed compression spring which, upon fixing on the cover element, is further pre-stressed by the rotating insertion of the protrusion in the guide paths, because the disc, acting as a stop, remains in contact with the cover body. The cover element is not pressed by this spring against the housing, but rather against the rotary grip of the securing bolt. This securing device effectively serves only to fix one cover element on a housing.